Respiratory disorders and chemical substances in workplace ambient air among rubber smoked sheet in Songkla province, Southern Thailand

Introduction
Exposure to woodsmoke has been associated with many respiratory diseases. The aim of this study was to describe respiratory disorders and some toxic compositions of woodsmoke among workers in the rubber smoked sheet factories in Songkla province, Southern Thailand.

Methods
Two large-scaled rubber smoked sheet factories were selected for measuring SO2, NO2, Ozone, Volatile organic compounds (VOCs) and polycyclic aromatic hydrocarbon (PAH). Of the total of 730 workers in 2 factories, 215 subjects were included. Both the workers and control, who were rubber planters in vicinity of the factories, were interviewed with questionnaire and underwent spirometry.

Results
The workers showed significantly higher prevalence of cough, cough with phlegm, phlegm, nasal congestion, chest tightness and wheezing. The workers also showed higher prevalence of respiratory diseases compared to control but not pulmonary function test. For workplace ambient chemicals, we found the geometric means of area sampling as follows: total PAHs 143.7 ng/m3 (95%CI 113.64-181.71), NO2 conc. 0.0122 ppm (95%CI 0.0102-0.0145), SO2 and O3 were not detected; and for VOCs as trichloromethane 0.0443 (95%CI 0.0098-0.2004), xylene 0.3514 (95%CI 0.2391-0.5165), toluene 0.1026 (95%CI 0.0578-0.1821), and cyclohexane <0.0003.

Discussion
This study indicated that the prevalence of abnormal respiratory symptoms and diseases among workers exposed to woodsmoke was significantly higher than control in rubber smoked sheet factories but not respiratory function tests. Each chemical substance under study is not beyond the occupational exposure level available.